请谁举一个第三个for loop from specification的例子，解释一下它是什么意思？
14.7.4 The for Statement个
Syntax个
ForStatement[Yield, Await, Return] :
for ( [lookahead ≠ let [] Expression[~In, ?Yield, ?Await] opt ; Expression[+In, ?Yield, ?Await] opt ; Expression[+In, ?Yield, ?Await] opt ) Statement[?Yield, ?Await, ?Return]
for ( var VariableDeclarationList[~In, ?Yield, ?Await] ; Expression[+In, ?Yield, ?Await] opt ; Expression[+In, ?Yield, ?Await] opt ) Statement[?Yield, ?Await, ?Return]
for ( LexicalDeclaration[~In, ?Yield, ?Await] Expression[+In, ?Yield, ?Await] opt ; Expression[+In, ?Yield, ?Await] opt ) Statement[?Yield, ?Await, ?Return]